Modern integrated circuits are typically fabricated upon silicon wafers. The wafers are usually quite thin and easily susceptible to breakage. To reduce the risk of breakage and simplify wafer handling, wafers are frequently transported in cassettes. For example, FIG. 1 illustrates cassette 11 with a plurality of wafers 12, 13, 14, 15, and 16. Typically, a cassette may hold 25 wafers. As illustrated in FIG. 1, wafer 12 is supported in cassette with its flat side 17 protruding through the bottom 19 of cassette 11.
Often it is desirable to be able to read small numbers which may be scribed on the upper portion of wafers. For example, in FIG. 1, scribed numbers 20, 21, 22, 23, and 24 are positioned on the upper portion of wafers 12, 13, 14, 15, and 16 respectively. When the cassette is filled with wafers, unfortunately, it may be difficult to read the small numbers which are scribed upon the top edges of the wafers.
In the past, practitioners have placed the bottom of cassette 11 upon a solid wedge. The solid wedge forces the wafers upward through the cassette and makes viewing numbers 20-24 somewhat easier. On other occasions, a flashlight is placed under the cassette (without a wedge) to aid in number identification. However, as wafers become larger and scribed numbers become smaller, there remains a continuing need for methods and apparatus for easier viewing of scribed numbers upon wafers. (Only a partially-filled cassette has been shown for convenience.)